Sash Window Add-On Weights

Posted by GEMMA SIM on

Double hung sash windows only need a few components to work smoothly. The most crucial are the weights. 


A double hung sash window is made up of one or more moveable panes of glass. To facilitate operation, the weight of the glazed panel is usually balanced by sash weight or counter-weight concealed within the window frame. The sash weight is connected to the window by a braided cotton sash cord, or a chain, that runs over a pulley at the top of the frame.

As anyone in the Window Repair Industry will know, re-balancing windows is an integral part of a sash window service. 

The largest percentage of the weight of a window sash is in the glazing, and the type of glass will therefore have a direct effect not only on the weight of the sash, but also on the required counterweight.  For example, glass in older windows may well be 2mm thick, which was the standard of yester-year.  In comparison the standard nowadays is 3mm thick which is heavier and will therefore require more weight to counterbalance it. If you have had new glass put in your window, and it is not functioning properly, chances are you need your window rebalanced. 

Incorrectly balanced windows are at best awkward and difficult to use, at worst they are dangerous - if a heavy window drops from its closed position it could cause a lot of damage.

In the vast majority of cases, re-balancing windows requires adding more weight as opposed to taking weight away. ...Enter the "add-on weight".

Small, half pound, one pound or two pound weights are added to ensure the correct weight is counterbalancing the window.

A specialist window repairer will know how to calculate the correct weight required.

Here at Lock and Latch we have worked closely with MST Window Repairs to bring a unique range of add on weights to the market.

Many add on weights on the market today in Australia are square.  However, the existing weights in the windows that need to be added to are not square, they are round.  Using our unique round and domed shape, our add on weights slot neatly and efficiently on to the existing weights making for a smooth and seamless movement within the box.  They have been designed this way because we found square weights would often cause friction problems within the box.

Our weights come in half pound and one pound options. We have found it difficult to find half pound weights and these are often required where the window is small. 

Our weights will soon be available to purchase.  Please e-mail us at if you would like to be emailed as soon as they are available.